This invention concerns treating tortillas and specifically relates to forming and cooking tortillas at a high volume, transforming them into tostada shells that serve as edible supports for salad like dishes.
U.S. Pat. Nos. 4,510,165 and 4,554,865 granted Apr. 9 and Nov. 26, 1985, respectively, to the assignee of the present invention were directed to the forming and cooking of taco shells. The apparatus and method disclosed in those patents were successful in high volume production of taco shells from the starting tortilla pieces. The later, in a substantially limp condition, could be positioned for capture by the male of the male-female pair of momentarily opened, complimentary forming molds. When closed into their nesting relationship, the forming molds bent the tortilla pieces into the characteristically U-shaped taco shells. The closed molds coupled to a conveyor carried the taco shells for cooking along a path through a bath of hot cooking oil. Upon exit from the cooking oil the forming molds opened from the nesting condition and the cooked taco shells were released from the molds and removed onto a takeaway conveyor.
Both taco and tostada shells are formed from tortillas but on the one hand taco shells are typically the characteristic deep U shape whereas tostada shells are a shallow, broad saucer shape, sometimes polygonal in outline and at other times having a circular outline with a fluted edge. Although both these Mexican derived food products are similar in a broad general sense, tostada forming and cooking requires different handling of the tortilla in order to achieve a consistently uniform product as demanded in high volume commercial production, 2,000 dozen per hour, for example.
The prior art of taco forming apparatus taught the design, purchase and use of complete mold sets dedicated to a small size range of taco shells with the result that entire forming and cooking equipment was designed to produce taco shells restricted to a single size of, say from either a 5 or a 6 inch diameter, tortillas. Should market and production requirements dictate different sizes of tortilla based products, an 8 inch diameter taco shell for example, completely separate and cooking and forming machines were required to accommodate those different sizes. This involved dedicating a large capital investment in forming and cooking equipment restricted solely to each of the different sized products. It would be an advancement if in the case of forming tostada shells from tortillas, where producers and the market desire a variety of tostada shapes, that the investment in equipment would not be completely duplicated for each of the is needed tostada shell shapes or sizes. Moreover, from a food processing plant operational standpoint it is very desirable to have flexibility in the capability of producing several different shapes or sizes of tostada shells through a quick equipment change-over routine from one shape or size of shell to another while using substantially the same cooking apparatus and cooking oil system as well as the same input and take away conveying systems in the plant. For example, the plant operator may wish to shift production from tostada shells over to taco shells and it is highly desirable that this may be readily accomplished using the same oil heating and cooking apparatus.
In its process aspects the invention concerns the simultaneous cooking and forming of tostada shells or the like through providing a bath of cooking oil heated to a cooking temperature, providing in a pliable, but partially toasted or otherwise heat treated condition, a supply of tortillas, and inserting the tortillas, in a series one at a time, into the openings between complimentary male and female molds in their opened condition mounted upon a conveyor, moving the molds into a closed yet spaced apart condition thereby capturing the tortillas in a cooking and forming space, moving the molds and tortillas contained therein through the bath of cooking oil thereby cooking and forming the tortillas into the desired shape of tostada shells, removing the tostada shells from the cooking oil, then shifting the molds into an open condition and removing the cooked shells from the molds, and taking away the tostada shells for further processing.
Another aspect of the process of this invention is providing for the forming of different sizes or shapes of tostadas or taco shells by providing in addition to the components stated above a second set of forming molds in a second conveyor array so equipped to produce products of the desired differing sizes or shapes, providing a wheeled carriage or tug having portions to receive both the first and second mentioned conveyors and the associated mold arrays, tugging the first mentioned conveyor onto the wheeled carriage, shifting the carriage so as to place the second mentioned conveyor for movement into the space formerly occupied by the first conveyor, then moving the carriage carrying the first conveyor to an out of the way position and then operating the second conveyor in the cooking and forming system to produce a product of the desired size or shape.
In its apparatus aspects the invention in summary embraces a cooker utilizing a hot oil bath as a cooking medium and equipped with an endless conveyor extending between a tortilla loading station and a cooked tostada unloading station. The conveyor has a lower run traversing the hot oil bath. Mounted on the conveyor are a plurality of complimentary pairs of forming molds of open wall construction for entry and egress of the cooking oil. The mold pairs cooperatively with the conveyor are constructed to afford an opened condition at the loading station to receive the tortillas, followed by a closed condition in which the mold sidewalls are maintained spaced apart permitting the tortilla to take on a desired cooked shaped and an opened condition at an unloading station to afford discharge of the cooked products.
A general object of the invention is to provide a highly reliable, continuously operable cooker for producing tostadas uniform in appearance and quality.
Another object of the invention is to provide for the flexible interchange of sets of forming and cooking molds employed in the production of tostada like products so that the hot oil cooker may serve usefully for cooking tostadas of different nominal sizes and shapes, and, as the need arises, to produce taco shells of various sizes.
Yet another object of the invention is to provide for an improved continuous process of preparing cooked tostadas from uncooked tortillas such that the end products are produced at a high volume and are uniform in appearance and quality.
Still another object of the invention is to provide for accurate control of the transformation of the tortilla from the flat shape into the shape of a saucer like tostada as it cooks.
A further object of the invention is to provide a tostada cooker of the type referred to above which is highly effective in large volume production but which occupies a small floor space in the production plant.